Wireless communication system, communication apparatus, relay apparatus, communication timing determination method and computer program

Abstract

In a wireless communication system in which a relay device provided on a mobile object communicates wirelessly with a plurality of communication devices present in places different from each other, each of the communication devices includes a communication device transmission unit which transmits test signals at a plurality of timings during a time frame when communication with the relay device is possible, a communication device reception unit which receives, from the relay device, communication situation information indicating communication situations at the plurality of timings, and a communication device control unit which controls the communication device transmission unit such that the communication device transmission unit communicates with the relay device at one of the plurality of timings, the communication situation of which is good and which is identified on the basis of the communication situation information, and the relay device includes a relay device reception unit which receives the respective test signals at the plurality of timings, a measurement unit which measures the respective communication situations at the time of reception of the test signals at the plurality of timings, a relay device control unit which generates the communication situation information on the basis of the communication situations, and a relay device transmission unit which transmits the communication situation information to the communication device during a time frame when communication with the communication device is possible.

The invention claimed is: 
     
       1. A wireless communication system in which a relay device provided on a mobile object communicates wirelessly with a plurality of communication devices present in places different from each other,
 wherein each of the communication devices includes 
 a communication device transmitter which transmits test signals at a plurality of timings during a time frame when communication with the relay device is possible, 
 a communication device receiver which receives, from the relay device, communication situation information indicating respective communication situations with the relay device at the plurality of timings, and 
 a communication device controller which identifies one, the communication situation of which is good, among the plurality of timings on the basis of the communication situation information and controls the communication device transmitter such that the communication device transmitter communicates with the relay device at the identified timing with the good communication situation, and 
 the relay device includes 
 a relay device receiver which receives the respective test signals transmitted from the communication device at the plurality of timings, 
 an indicator which measures the respective communication situations at the time of reception of the test signals at the plurality of timings by the relay device receiver, 
 a relay device controller which generates the communication situation information on the basis of the communication situations measured by the indicator, and 
 a relay device transmitter which transmits the communication situation information to the communication device during a time frame when communication with the communication device is possible. 
 
     
     
       2. The wireless communication system according to  claim 1 , wherein
 the communication device transmitter transmits the test signals again at a plurality of timings at shorter intervals during a partial time frame of the time frame when communication with the relay device is possible, on the basis of the communication situation information. 
 
     
     
       3. A communication timing determination method in a wireless communication system in which a relay device provided on a mobile object communicates wirelessly with a plurality of communication devices present in places different from each other, comprising:
 by each of the communication devices, transmitting test signals at a plurality of timings during a time frame when communication with the relay device is possible; 
 by the relay device, receiving the respective test signals transmitted from the communication device at the plurality of timings; 
 by the relay device, measuring respective communication situations at the time of reception of the test signals at the plurality of timings; 
 by the relay device, generating communication situation information indicating the respective communication situations with the relay device at the plurality of timings on the basis of the communication situations; 
 by the relay device, transmitting the communication situation information to the communication device during a time frame when communication with the communication device is possible; 
 by the communication device, receiving the communication situation information; and 
 by the communication device, identifying one, the communication situation of which is good, among the plurality of timings on the basis of the communication situation information and controlling a communication device transmitter such that the communication device transmitter communicates with the relay device at the identified timing with the good communication situation.